System for viewing detected objects

ABSTRACT

An array of sonar receiving elements provides signals to a corresponding array of display lights upon receipt of target signal returns from a field under investigation. The display is viewed by an observer having one eye placed behind a rotating transparent disk having front and rear surfaces at an angle relative to one another, and which angle varies as the disk is rotated, thereby changing the apparent position of the display lights as a function of time.

United States Patent 1 1 1111 3,739,324 Coltman June 12, 1973 SYSTEM FORVIEWING DETECTED 2,769,160 10/1956 Fryklund 340/3 0 OBJECTS 2,976,3623/l96l Stamps 17817.6

3,300,779 1/1967 Sirkis 343/19 [75] Inventor: John W. Coltman,Pittsburgh, Pa.

[73] Assignee: Westinghouse Electric Corporation, PrimaryExaminer-Richard A. Farley v Pittsburgh, Pa. Attorney-F. l-l. Henson, D.Schron and E. P. Klipfel [22] Filed: Dec. 22, 1970 21 Appl. N0.2 100,679[571 ABSTRACT An array of sonar receiving elements provides signals 521US. Cl 340/3 c, 340/5 NP 343/79 P" may P "8" "P" P [51] Int. Cl. 6 0139/66 target signal returns from a flew under invesfigafion 58 Field ofSearch 343/19; 340/1 R, The P is View! by having Y 3 40 /3 C 3 R 5 H, 5356/4 350/6 170 placed behind a rotating transparent disk having frontand rear surfaces at an angle relative to one another, and which anglevaries as the disk is rotated, thereby [56] References Cited changingthe apparent position of the display lights as UNITED STATES PATENTS afuncm" 2,637,023 4/1953 Peters et al. 34317.9 6 Claims, 11 DrawingFigures TRANSMITTER 1 SIGNAL PROCESSING Patented June 12, 1973 3,739,324

2 Sheets-Sheet 1 FIG. I

Patented June 12, 1973 5O 54 nrnnaunnnnz: FIG. 4

FIG. 5

5O 56 mfluanaanl 1 SYSTEM FOR VIEWING DETECTED OBJECTS BACKGROUND OF THEINVENTION 1. Field of the Invention Detection systems and particularlythe displays therefor.

2. Description of The Prior Art In multi-element receiver systems, forexample sonar, an array of elements is provided with each being operableto receive energy from a discrete area of a field under investigation.The elements are arranged in an array with means for focusing receivedenergy onto individual ones of the elements which in turn providecorresponding output signals. A display is provided and is preferably ina one to one correspondence with the receiver elements, that is thedisplay lights are arranged on a flat panel in a geometry correspondingto the geometrical disposition of the receiving element array. Thelighting of a light on the display indicates a target in the field underinvestigation, however, the observer can only get an indication of theangular orientation of the a target but not its range. The presentinvention provides the desired depth perception.

SUMMARY OF THE INVENTION Receiving means having a plurality of energyreceiving portions in the form of an array of elements, is provided eachfor receivingenergy from a discrete area of a field under investigation.Signals from any target within the field under investigation, whenfocused on the array, will cause a corresponding one or more of thereceiver elements to provide an output signal which is processed andcoupled to a display means having a plurality of light emitting areassuch as light emitting elements, preferably in the same geometric arrayas the receiving elements, tothereby indicate the presence of a targetin the field. A viewing means for viewing the display is positioned atan observers location and is placed in front of the observer to vary,asa functionof time, the angle at which light rays from the displaymeans are seen by the observer, thus changing the apparent position ofthe display lights as a function .of time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a preferredembodiment of the present invention;

FIG. 1a illustrates a geometric arrangement of elements illustrated inFIG. 1;

FIG. 2 is a view of the disk illustrated in FIG. 1;

FIG. 3 is a top view of the disk of FIG. 2;

FIGS. 4 through 7 illustrate sections through thedisk of FIG. 3;

FIG. 8 is a light ray diagram illustrating the apparent change inposition of a display as seen by an observer; and

FIGS. 9 and 10 are variations of a viewing means for observing thedisplay.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 there is illustratedcomponents of one type of detection system utilized for detectingtargets in an underwater environment, however, other arrangements inother environments, for example flaw detection, are also applicable. Atransmitter 10, in response to a command pulse on line 12, provides apulse signal to projector 14 which in response thereto projects a pulseof acoustic energy onto afield 16 under investigation. In order todetect acoustic returns reflected from targets in the field underinvestigation, there is provided receiver apparatus which includes alens system 22 operable to focus returned acoustic energy ontoindividual ones of a plurality of receiver elements 24 arranged in atwo-dimensional geometric array as'illustrated by way of example in FIG.1a. In FIG. 1 it is seen that returns from targets T1 and T2 are focusedby the lens system 22 onto different receiver elements. (T1 and T2 areac tually relatively distant from the lens system). Since target T1 iscloser to the receiver apparatus than is target T2, the elementreceiving its energy will provide a corresponding output signal beforethe element receiving energy from target T2. The outputs from thereceiving elements 24 are processed by signal processing networks 26which may include such circuitry as frequency filters, time varying gaincircuits and threshold detectors, to name a few. Such receiver apparatusincorporating a lens system with a plurality of receiver elements whoseoutput signals are processed, are well known to those skilled in theart.

The signal processing network couples any output signals from thereceiver elements 24 to a display means 32 which includes a plurality oflight emitting areas shown by way of example as elements 34, preferablyarranged in the same geometric pattern as the receiver array with eachlight emitting element being connected to be responsive to an outputsignal from a corresponding receiver element, except that the entiredisplay array is inverted so as to compensate for the inversionperformed by the lens.

The light emitting elements 34 are .fast responding, that is, they canbe turned on and off at a rate corresponding to the output signalsprovided by the associated receiver elements. The light emittingelements may be solid state injection luminescent diodes,electroluminescentelements, gas discharge lamps, to name a few. A targetreturn therefore will cause the activation of one or more light emittingelements 34in aposition on the display means 32 correspondingto theactual position of the ,target in the field under investigation.

Since the lighternitting elements 34 are in a one to one correspondencewith the receiver elements'24, an observer at .location 40 may view thedisplay 32 and when a target causes one or more lights to .go on,'he canget anindication of the bearing of the target. The target 'howeverrnaybe anywhere between the receiver apparange, there is provided a viewingmeans operable to vary, as a function of time, the angle at which lightrays from :thedisplaymeans 32 relatively enter the eyes of the observerwith the varying angle changing the apparent;.position of the displayaway from the observerso that the observer will see a target return at aposition corresponding tothe position of the actual target relative tothe-maximum range.

In the embodiment illustratedinFIG. l, the viewing means includes anoptical-device in the-form of transparent disk 44 which is positioned infront of one eye, of the observer, and which is rotated by means ofmotor 46. Each complete rotation of the disk 44 represents aninvestigatory sweep from the receiver apparatus out to the maximum rangeof the field under investigation (taking into an account the round triptravel time of the acoustic energy). When the disk 44 returns to itsinitial reference position an acoustic pulse is provided by theprojector 14. In order to synchronize this operation, a synchronizingmeans 48 coupled to the motor 46 or the shaft thereof provides anelectrical signal on line 12 for each complete rotation of the shaft andthis electrical signal forms the command pulse for transmitter 10.

The disk 44, another view of which is illustrated in FIG. 2, isrotatable about an axis A and includes a front surface 50 and a rearsurface 51. The front surface 50 slopes downwardly from an edge to acentral portion 56 to which the motor 46 is coupled and which need notbe optically transparent. Starting from a reference position, forexample at 58 and proceeding around the periphery of disk in thedirection of the arrow, the thickness of the disk, as measured at theoutermost edge thereof, progressively increases up to a maximum at point60.

A top view of the disk, including the reference numerals of FIG. 2, isillustrated in FIG. 3. Sections of the disk along lines lV-IV to VIIVIIare respectively illustrated in FIGS. 4 through 7. The angle defined bythe front and rear surfaces 50 and 51 increases from a minimumillustrated in FIG. 4 to the maximum illustrated in FIG. 7. The minimumto maximum angle is achieved in one revolution of the disk, after whichthe cycle is repeated. For some applications the disk could be dividedup into a plurality of sections, each section having front and rearsurfaces which progress from a minimum to a maximum angularrelationship.

The prismatic action of the surfaces of the disk, when placed before theobservers eye, changes the angle at which light rays from the displayenter the eye. This operation may be demonstrated with reference to FIG.8.

In FIG. 8 let it be assumed that a target return has caused element 34of display 32 to emit light. A light ray 64 enters the left eye of theobserver 66. The surfaces of the disk 44 provide a prism structure infront of the right eye of the observer causing light ray 65 which entersthe right eye of the observer, to appear to come from a more distantpoint along the path 68 which intersects the extension of light ray 64at a point designated at 34 and which is the apparent position of lightfrom the element 34. At the instant of time illustrated in FIG. 8, lightfrom any element on display 32 will appear to emanate from the apparentdisplay 32'.

For a given index of refraction of the transparent disk material, theangle that the front surface makes with the rear surface of the diskdetermines the apparent position of the display and, accordingly, anylight on the display. The maximum angle results in a maximum apparentdisplacement designated R,,. which corresponds to the maximum range R,,in the field under investigation.

At an instant of time past that illustrated in FIG. 8 a flat section ofdisk, as illustrated in FIG. 4, will be brought before the observers eyeand substantially no refraction of a light ray such as 65 will takeplace and thus the observer sees the light or lights on display 32 attheir actual position. It is seen therefore that with each completerotation of the disk 44 the display will be swept out to a position 32and is available for receipt of target information any time during thesweep such that an observer will see a light at a position in the 4.field from 32 to 32' which corresponds and may be made proportional tothe position of an actual target in the field from the receiver 20 outto a maximum range R of FIG. 1. The scale of this model is determined bythe design of the surfaces 50 and 51 of the disk.

Although the single unidirectionally rotating disk provides the simplestmeans for charging the angle at which light rays from the displayrelatively enter the eyes of the observer, other optical means may beprovided. For example, FIG. 9 illustrates a transparent block 81 whichis rotated about an axis 82 to displace the position of light ray 84 to84'. In FIG. 10 a dual mirror arrangement is provided wherein lightstrikes sta tionary mirror 86 and is reflected from oscillating mirror88, oscillating about axis 89 in the direction of the arrow to vary theposition of light ray 91 to 91.

While the invention has been described, for simplicity, in terms ofdiscrete receiving elements and discrete lamps, it will be understoodthat the same principles are applicable when either the receiving ordisplay arrays, or v both are continuous. For example, a pressuresensitive crystal may be scanned by a cathode ray beam to act as areceiver, and the display consists of a cathode ray tube of the typefamiliar in television kinescopes. It is necessary only that the time atwhich a particular display area is lit corresponds to the time at whichits corresponding receiver area was excited.

I claim as my invention:

1. A system for viewing detected objects comprising:

a. receiving means having a plurality of energy receiving portions eachfor receiving energy from a discrete area of a field underinvestigation, for providing corresponding output signals;

b. display means including a plurality of light emitting areas connectedto be responsive to said output signals for emitting light;

c. an observers location for an observer to view said display means;

d. viewing means positioned at said observers location for varying, as afunction of time, the apparent position of said display means, as seenby said observer;

e. said viewing means including a transparent disk for placement infront of one eye of said observer and rotatable about an axis;

f. said disk having a front and rear surface;

g. the angle that said front surface makes with said rear surface beingvariable.

2. Apparatus according to claim 1 wherein:

a. said light emitting areas are discrete light emitting elements.

3. Apparatus according to claim 1 wherein said viewing means includes:

a. a transparent optical device;

b. means for rotating said optical device about an axis;

c. said optical device being positionable in the vicinity of said eye ofsaid observer to vary the angle at which light rays enter said eye assaid device is rotated.

4. Apparatus according to claim 2 wherein:

a. said rotation is unidirectional.

5. Apparatus according to claim 2 wherein:

a. said rotation is bi-directional.

6. Apparatus according to claim 2 which additionally includes:

a. means responsive to said rotation for periodically projectingacoustic energy onto said field under investigation.

1. A system for viewing detected objects comprising: a. receiving meanshaving a plurality of energy receiving portions each for receivingenergy from a discrete area of a field under investigation, forproviding corresponding output signals; b. display means including aplurality of light emitting areas connected to be responsive to saidoutput signals for emitting light; c. an observer''s location for anobserver to view said display means; d. viewing means positioned at saidobserver''s location for varying, as a function of time, the apparentposition of said display means, as seen by said observer; e. saidviewing means including a transparent disk for placement in front of oneeye of said observer and rotatable about an axis; f. said disk having afront and rear surface; g. the angle that said front surface makes withsaid rear surface being variable.
 2. Apparatus according to claim 1wherein: a. said light emitting areas are discrete light emittingelements.
 3. Apparatus according to claim 1 wherein said viewing meansincludes: a. a transparent optical device; b. means for rotating saidoptical device about an axis; c. said optical device being positionablein the vicinity of said eye of said observer to vary the angle at whichlight rays enter said eye as said device is rotated.
 4. Apparatusaccording to claim 2 wherein: a. said rotation is unidirectional. 5.Apparatus according to claim 2 wherein: a. said rotation isbi-directional.
 6. Apparatus according to claim 2 which additionallyincludes: a. means responsive to said rotation for periodicallyprojecting acoustic energy onto said field under investigation.